Cutaneous Drug Erruptions Flashcards
Types of allergic cutaneous drug eruptions?
Immunologically mediated reactions (allergic)
-Type 1: anaphylactic reaction
Type 2: Cytoxic reactions (pemohigus/pemphigoid)
Type 3: Immune complex mediated reactions (rash)
Type 4: Cell mediated delayed hypersensitivity reactions
-T cell mediated
Non- immunological reactions?
- Eczema
- Drug induced alopecia
- Phototoxicity
- Skin erosion due to topical 5-fluorouracil
- Atrophy due to atopical corticosteroids
- Psoriasis
- Pigmentation
- Chellitis/xerosis
Presentation of reactions?
Pigmentation Itch/pain Photosensitivity Urticarial Exanthematous
Who to consider for a drug reaction?
Any patient taking medication who suddenly develops a symmetrical skin eruption
Risk factor for drug eruptions?
- Age (young adults)
- Gender (females)
- Genetics
- Concomitant disease (viral)
- Immune status
Risk factors for drugs involved in eruptions?
- Chemistry (Blactam.NSAIDS)
- Route (topical v oral/systemic)
- Dose
- half life
Most common type of drug eruption?
Exanthematous
What type of hypersensitivity is exanthematous drug eruption?
T cell mediated delayed type hypersensitivity (type iv)
Description of exanthematous drug eruption?
Mild & self-limiting
- Widespread symmetrically distributed rash
- Mucous membrane spared
- Pruritus
- Mild fever
Indicators of a potentially severe exanthematous drug eruption?
- Involvement of mucous membrane & face
- Facial erythema & oedema
- Widespread confluent erythema
- Fever
- Skin pain
- Blisters, purpura, necrosis
- Lymphadenopathy
- SOB, wheezing
Drugs associated with exanthematous eruptions?
- Penicillins
- Sulphonamides
- Erythromycin
- Streptomycin
- Allopurinol
- Anti-epileptics
- NSAIDs
- Chloramphenicol
What type of hypersensitivity is urticarial drug reactions?
Urticarial
-usually an immediate IgE mediated hypersensitivity reaction (Type 1) after rechallenge with drug (B lactam ABs)
OR
direct release of inflammatory mediators from mast cells on first exposure
What might an urticarial reaction be associated with?
Angioedema or anaphylaxis
Pustular or bullous drug erruptions?
Acneiform (glucocorticoids)
Acute generalized exanthematous pustulosis (ABs, CCB)
What is drug induced bullous pemphigoid caused by
ACE inhibitors
Penicillin
Furosemide
What disease can be triggered by vancomycin?
Liner IgA disease
Characteristics of a fixed drug eruption?
Well demarcated round/ovoid plaques
- Red painful
- Hands, genitalia, lips, oral mucosa
Presentation of fixed drug eruptions?
Eczematous lesions
Papules
Vesicles
Urticaria
Drugs associated with fixed drug eruptions?
Tetracycline, doxycycline
Paracetemol
NSAIDs
Carbamazepine
Cutaneous & systemic symptoms of severe cutaneous adverse drug reactions?
- Stevens-Johnson Syndrome
- Toxic epidermal necrolysis
- Drug reaction with eosinophilia & systemic symptoms (DRESS)
- Acute generalised exanthematous pustulosis
Acute phototoxic drug reactions?
Skin toxicity- photosensitivity
Systemic toxicity
Photodegradation
Chronic phototoxic drug reactions?
Pigmentation
Photoageing
Photocarcinogenesis
What type of immunity phototoxic cutaneous drug reactions?
Non-immunological skin reaction arising in an individual exposed to enough photo-reactive drug & light of the inappropriate wavelengths
Patterns of skin phototoxicity?
- Immediate prickling with delayed erythema & pigmentation
- Exaggerated sunburn
- Exposed telangiectasia
- Delayed 3-5 days erythema & pigmentation
- Increased skin fragility
